A power device such as an IGBT or MOSFET that switches input voltage is used in a power converter such as an inverter or converter. Specifically, the power converter includes power devices 1 and 2 formed of IGBTs of a totem pole connected bridge configuration, as shown in, for example, FIG. 8. Also, the power converter includes drive circuits 3 and 4, which apply control voltage to gates that are control terminals of the power devices 1 and 2, thereby driving the power devices 1 and 2 so as to be turned on and off in a complementary way.
Reference numbers 5 and 6 in the drawing identify freewheeling diodes connected in anti-parallel to the power devices 1 and 2 respectively. Also, 7 and 8 are output amplifiers that configure output stages of the drive circuits 3 and 4 respectively. Further, the power converter, by switching an input voltage Vin via the power devices 1 and 2, operates so that a predetermined output voltage Vout is obtained from a series connection point of the power devices 1 and 2.
Herein, it is undeniable that when the power devices 1 and 2 simultaneously carry out a turn-on operation for some reason, a large short-circuit current flows through the power devices 1 and 2. Therefore, there is a demand for the power devices 1 and 2 to be provided with a high short-circuit resistance in order to prevent thermal breakdown due to the short-circuit current. However, there is a problem in that, in order to increase short-circuit resistance, it is necessary to increase the chip size of the power devices 1 and 2, together with which the package size is also increased.
Therefore, excessive current flowing through the power devices 1 and 2 has thus far exclusively been detected using current detection means. Further, it has been proposed that overheating breakdown of the power devices 1 and 2 due to short-circuit current is prevented by stopping the drive of the power devices 1 and 2 by the drive circuits 3 and 4 when excessive current is detected (for example, refer to PTL 1 and 2).